Lag Time Forecasting Using Fuzzy Regression Based Formulae

River basin lag time is an important factor in the linear modelling of river basin response. in this study, the modelling of lag time using fuzzy regression is applied. for this purpose, the data for rainfall-runoff events of khanmirza basin (nine events) were collected and analysed. followingon, events were divided into two groups: one for formulas based on fuzzy regression and another for the validation of these formulas. the results obtained from this study, based on re and rmse statistical measures, showed that the efficiency of newly developed formulas based on fuzzyregression methods is higher than for other formulas used for the calculation of time of concentration.